Electrical relay



Oct.A 14, l1941. c, s. sNAvELY ELECTRICAL RELAY Filed Dec. 23, 1939 2Sheets-Sheet l fig 4.

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INVENTOR HIS ATTORNEY Oct 14, 1941- c. s. sNAvELY ELECTRICAL RELAY FiledDec. 23, 1939 2 Sheets-Sheet 2 INVENTOR Claence L Snape@ IS ATTORN EYPatented Oct. 14, 1941 UNITED STATES, PATENT OFFICE ELECTRICAL RELAYGlalfence S. Snavely, PittsburghPa., assignor to The Union Switch &Signal Company, Swissvale; Pa., acorporation of PennsylvaniaLApplication December 23, 1939, Serial No. 310,713

(Cl. ZOO- 104) 5 Claims.

My invention relates to electrical relays,y and particularly toelectrical relays suitable for use in centralized traffic controllingsystems for railroads.. such, for example, as that. disclosed in anapplication for Letters Patent of the United States, Serial No. 222,860,led by myself and another on August 3',A 1938, for Remote controlsystems.

One object of my invention isl to provide an improved'A relay of' thetype' described of simple, ruggedandk compact construction, which willoperate without appreciable wear or change in operating characteristicsover along period of timel Other objects and characteristic features ofmy invention will appear as the description proceeds. The relay formingthe subject matter of my present'application is an improvement upon thatdisclosed and claimed in my prior Patent No.

2,178,289, granted on October 31, 1939, for electrical relays.

I shall describe one form of relay embodying my invention, and onemethod for securing` certain parts of said relay together, and shallthen point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a front elevational view showingone form of relay embodying myl invention, the front plate of the relaybeing removed to better illustrate the con 'struction of the operatingparts of the relay.

Fig. 2 is a vertical sectional view of the relay shown in Fig. 1 takensubstantially on the line II-II of Fig. 1. Fig. 3 is a top plan View ofthe relay shown in Fig. 1. Fig. 4 is a sectional view of the relay shownin Fig. l taken substantially pieces are formed on cores which aremoulded into the top and bottom walls of an insulating frame,and the onepair of pole pieces is constantly magnetized by a permanent magnet whilethe other pair is at times energized by an electromagnet of which theassociated cores form a part. The two armatures are secured to theopposite ends of a moulded contact operating member which is mounted forsliding movement in a manner to permit the two armatures to move -gtoward` and away from the associated pole pieces.

' he contact operating member is provided between thevtwo armatures witha plurality of projections which form vertically spaced slots. Each ofthese slots receives the intermediate portion of a cooperating flexiblecontact nger which is moulded at one end into one of the side walls ofthe frame and which cooperates at its free end with a xed contact fingeralso moulded into a side wall oi the frame. The relay is calibrated toprovide the desired operating characteristics by charging the permanentmagnet and then discharging it to a value which will give the desiredpiek-up current, and also by varying the air gaps between the cores andthe backstrap of the elec- 1 on the line IV-IV of Fig. 1. Figs. 5, 6 and7 are back, side and top views, respectively, of the contact operatingmember 21 forming part of the relay shown in Fig. 1. Fig. 8 is a detailview of the member 32 forming part of the relay shown in Figs. 1 and 2.Figs. 9, 10 and 11 are diagrammatic views illustrating certain featuresof the relay embodying my invention. Figs. 12 and 13 are enlargedv viewsshowing the means employed for securing the backstrap I3 to the cores Iland Ila of the electromaget A of the relay shown in Fig. 1 together witha mould for applying this means.

Similar reference characters refer to similar parts in each of theseveral views.

Referring rst to Figs. 1, 2 and 3, the relay in the form here showncomprises a suitable case consisting of a front cover plate I and a backcover plate 2 clamped by suitable means not shown against the oppositesides of a rectangular frame 'I of suitable insulating material, suchfor example as a phenol condensation product. This case encloses all ofthe operating parts of the relay, and in order to permit readyinspection of the operating parts without the necessity for removing thecover plates, the front cover plate is formed with a window 8 which isclosed by a window glass 9.

Mounted on the top wall 1a of the frame 'I is an electromagnet Acomprising a pair of coils I0 and Illa disposed on spaced parallel coresI I and I Ia, the lower ends of which extend downwardly through the topwall 'Ia and terminate on the underside thereof in enlarged pole piecesI2 and The cores II and IIa may be secured to the top wall 1a in anyconvenient manner, but-as here shown they are moulded into the top wall.

The relay also comprises an auxiliary pair of spaced parallel cores I6and Ita which are moulded into the bottom wall 1d of the frame 1 inaxial alignment with the cores I0 and Illa of the electromagnet A, andwhich terminate at their upper ends in enlarged auxiliary pole pieces I1and I'Ia. The lower ends of the cores I6 and Ia are also enlarged andare engaged by the opposite ends of a permanent magnet I8. The permanentmagnet I8 is held against the enlarged ends of the cores I6 and I'a bymeans of a curved flexible strip 2li and a bottom plate 2|, and in orderto provide an efficient magnetic connection between the auxiliary coresand the permanent magnet, the engaging faces of the auxiliary cores andthe permanent magnet are ground to lie in the same plane. The bottomplate 2| fits at its ends in transverse grooves 23 provided in dependinglegs 1e and 1f which form extensions of the side walls 1b and 1c of thevframe 1, and at its sides in grooves 24 and 24a formed respectively inthe front and back cover plates I and 2.

'I'he pole pieces I2 and I2a cooperate with a main armature 25, Whilethe auxiliary pole pieces I1 and I1a cooperate with an auxiliaryarmature 26. vThe two armatures 25 and 26 are moulded onto, or otherwisesecured to, the opposite ends of a Contact operating member 21 ofsuitable insulating material in such manner that the upper face of thearmature 25 and the lower face -of the. armature 26 lie in parallelplanes, and these armatures act to move the contact operating membervertically between a lower position in which the armature 26 engages astop 28 moulded onto the bottom wall 1d of the frame 1 and an upperposition in which the armature 25 engages the lower faces of the polepieces I2 and I2a, according as the electromagnet A is deenergized orenergized. The parallel faces of the two armaturesare chromium plated topresent smooth wearing surfaces to their respective engaging surfaces..Furthermore the pole pieces with which the armatures cooperate are alsochromium plated and polished, the chromium plating on the pole pieces I2and I2a. serving in conjunction with the chromium plating on thearmature 25 to take the place of the usual core pins to prevent thearmature 25 from sticking in its attracted position due to any residualmagnetism which may be present in the cores of the electromagnet A whenit is deenergized. Y The contact operating member 21 is guided to movevertically by means of a vertical guide rod 3D which extends with someclearance through aligned opening 21a formed in vertically spaced lugs21h provided on the rear side of the operating member 21. This guide rodis mounted at its upper end in an opening 3l provided in a transverselyextending bar 32,*and at its lower end in an opening 33 provided in thebottom wall 1d of the frame 1. The bar 32 fits at its ends in recesses33 formed in the side walls 1b and 1c of the frame 1 above the coilconnectors I #la and I-tb and is held in place in the recesses by meansof the back cover plate 2. The lower end of the guide rod is held inplace in the opening 33 by means of a mass 33a of material which can beapplied in a liquid or molten state and which will subsequently harden.A preferred material for this purpose is 'l per cent antimony lead. Toreduce friction and wear to a minimum lthe guide rod 33 is provided witha smootlr polished surface, such for example as that obtainable bychromium plating.

'I'he bar 32, in addition to serving as a positioning means for theupper end of the guideI rod 21, is provided on the side adjacent to the:armature 25 with laterally projecting pads 32a and 32h which cooperatewith the side of the armature 25 to hold it and the contact operating:member 21 in the desired angular position relative to the pole piecesand other parts of the relay. These pads are preferably chromium platedand polished to reduce friction to a minimum.

Formed on the rear side of the contact operating member 21 are aplurality of projections 35 which form slots 36. The slots 36 receive aplurality of vertically spaced superposed contact fingers 31intermediate the ends of the fingers. The contact ngers 31 are mouldedinto the opposite side walls 1b and 1c of the `frame 1 in such mannerthat alternate fingers are located in different legs and extend inopposite directions, and, as here shown, each of the upper fingerscooperates with an associated fixed front contact finger 38 which ismoulded into the side wall of the frame 1 opposite the side wall inwhich the finger is located, while the remaining fingers each cooperatewith a fixed back contact finger 39 which is likewise moulded in theside wall of the frame 1 opposite the side wall in which Ythe associatedflexible nger is moulded. To decrease contact resistance, the flexiblecontact fingers are each provided with Contact buttons 49 of lowresistance conducting material such as silver, which contact buttonscooperate with contact button ill, also of low resistance conductingmaterial such as silver, provided on the associated xed contact fingers.'Ihe contact fingers each extend through the associated side Walls ofthe frame 1 and are provided with rounded outer ends which constituteplug portions to enable the relay to be readily plugged into suitableconnectors such for example as those described in my copendingapplication for Letters Patent of the United States, Serial No. 291,721,filed on August 24, 1939, for a Mounting means for relays. The outerends of the two coil connectors Mc and I 4b similarly extend outwardlythrough the associated side walls and are provided with rounded outerends.

The operation of the relay as a whole is as follows: The parts are soproportioned that when contact operating member 21 is in its mid-strokeposition, the flexible contact fingers 31 will be substantially unexedand the contact buttons 40 on those flexible ngers which cooperate withthe fixed front contact fingers 38 will be spaced the same distance fromthe buttons 4I on the front contact fingers as the contact buttons 40 onthe flexible fingers which cooperate with the fixed back contact fingers39 are spaced from the contact buttons 4I) on these latter contactfingers. The parts are further so proportioned that when ytheelectromagnetA is deenergi-zed'the-flux from the .permanent .magnet I;8traversing the auxiliary pole pieces v|| and v|6a, together 'with theweight -of the two armatures A'.25 and 26 andthe weight of the contactoperating .member 21, will .exert a suflicient biasing .force on thecontact operating member to move it downwardly .to its 'lower positionin which the armature 26 engages the stop 2.8, and that beforethecontact operating vmember reaches -its lower position, the contactbuttons .40 on each of the three lower fiexible fin- :gers will moveinto engagement with the contact fbuttons on the associated fixedcontact fingers 39. It will .be seen, therefore, that v.the movement ofthe contact operating member 21 toits lowerlmost .position will causethe centers of those flexible fingers which cooperate with fixed 'back.con tact fingers to become forced downwardly at .the .point where theyare engaged Iby the projections 3.5, thereby providing a, limited.amount of wiping `action .between the engaging contact 'buttons on theflexible contact fingers and the buttons on :the fixed .back Acontactfingers as the contact operating member moves to its lowermost position,and hence insuring that when the operating member .occupies thislowermost position, vthe contact buttons on the flexible fingerswillengage the contact buttons on the associated fixed back contactfingers with sufficient force to provide an .effective low resistancecontact. The downward movement of the contact operating member 21 willcause each of the fiexible contact fingers which does not engage with afixed back contact finger to continue to move downwardly at its free.end until the armature 26 reaches its lower extreme position in whichit engages the stop 28. 4It will be seen, therefore, that when `thepermanent magnet |8 is in place and the parts are properly adjusted, ifthe electromagnet A is then deenergized, the front contacts 31-38 of therelay will be open and the back contacts 31-33 will be closed.

When the electromagnet A becomes energized, .the resultant fiux which isset up by the current traversing the coils l and |0a will cause thearmature 25 to move upwardly, in opposition to the bias of the permanentmagnet and the weight of the two armatures and the associated Contactoperating member', and will thus move the contact operating member 21 toits 4upper extreme vposition in which it engages the pole pieces |2 and|2a. This upward movement will cause the .conn tact buttons 46 on theflexible contact finger to move out of engagement with the button 4| onthe back contact fingers 39, and into engagement with the buttons 4| onthe front Contact members, thereby opening the back contacts 31-39 andclosing the front contacts 31-38. rI'he parts are further soproportioned that the contact buttons M on the flexible contact fingerswill move into engagement with the buttons 4| on the front contactfingers 38 before the armature 25 reaches its upper extreme position,and it will be seen, therefore, that the movement of the armature 25 toits upper extreme position will cause the fiexible contact fingers 31 tobecome bowed upwardly intermediate their ends and will thus cause alimited amount of wiping action between the engaging contact buttons 43and 4| as the armature 25 completes its upward movement, as well asinsuring a good contact pressure to provide an efiicient low resistancecontact.

It will be noted from an inspection of Fig. that alternate ones of theprojections 35 on the contact operating member 21 are disposed onAoppositeisides =of the center line. This arrangement affords Vanumberof advantages which can Abest be l.explained by reference to the viewsshown in Figs. 9, and 11.

Referring to these views, Fig. 10'shows one of lthe front contacts 31-38so adjusted that when the :associated linger 31 is unstressed, thebutton 4.0 .carried thereby will just touch the button 4| vontheassociated iixedfront contact finger. With l:the finger adjusted inVthis manner, vwhen the contact is opened vby `driving the operatingmember 21 downwardly to the yposition shown in Fig. l-l, ithe finger 31will free itself from the lower pro- :jection 3.5 as 'shown bythe spa-ce35a between the projection and the finger. Thus there is no `tendencyfor the projection to bind the finger when 'the contact is open. Whenthe operating member 2.1 'is driven upwardly from the position shown inFig. 10, as is the case when the armature'25 is attracted, the contactmember 31 vthen becomes compressed .as shown in Fig. '9, and :under:these conditions the finger 31 frees itself from the upper projectionV35. Thus there is no tendency to bind when the contact is compressed..Since there is no tendency for the contact finger .to bind between .theprojections 35, it is unnecessary to accurately control the thickness ofthe projections or the distance between them. Furthermore,.maladjustmentof the contacts W'ill not .so adversely affect the operatingcharacteristics of the relay as would otherwise be the case. Con- Sideragain Fig. 9. The bend in the contact finger 31 is exaggerated t0 showthe non-binding advantage. Actually the spacing between the upperprojection 35 and the finger is relatively small. Assume that the fixedfront contact finger 38 is not adjusted as intended, but is bentupwardly from the position shown. When the contact button on the finger31 is driven upwardly by the lower projection 35, it will not strike the.button on the fixed front contact finger 38 at the point shown, sincethis latter nger is bent out of position. The finger 31 will, however,be bent as may be seen since the upper projection 35 pre- 'vents freecounterclockwse rotation of the finger 31. The force necessary from thearmature '25 vof the relay to push the drive element 21 from oneposition to the other is only slightly less than if the fixed frontcontact finger has been correctly adjusted. A fixed front contact fingeris shown in the diagram, but the same reasoning applies to a fixed backcontact finger. The relay therefore has more stable characteristics whenmaladjustments occur than other relays of its type.

Refer again to Fig. l0. Assume that the contact button on the movableContact finger 31 sticks to the contact button d! on the fixed contactfinger 38 due to frost or some other reason. When the contact operatingmember 21 is pulled downwardly by means of the permanent magnet, theupper projection 35 will force the contact finger 31 downwardly and willactually force the contact buttons 40 and 4| apart.

In assembling a relay constructed in accordance with my invention thecont-act alignment of the Contact fingers with respect to the frame 1 isfirst checked in a suitable tool provided especially for that purpose.The contact operating member 21 is then placed inside the frame 1 withthe slots 36 facing toward the rear, and receiving the flexible contactfingers 31. The bar 32 is next placed with its ends in the notches 34 inthe frame 1 and with the pads 32a and 32o facing the armature 25. Theguide rod 30 is then inserted from the bottom of the relay throughlquire no adjustment.

the opening 33 in the bottom wall 1d and through the twoholes 21a in thelugs 2lb of the contact operating member 2l into the hole SI in the bar32. The relay is then turned upside down land a magnetic force isapplied to the cores II and IIa to hold the armature 25 against the polepieces i2 and i217.. The securing means 33a. is next applied, therebyinsuring that the contact `operating member 3'! will be secured in placein the properposition with respect to the pole pieces. While themagnetic force is still applied .to the cores, spacers of a definitethickness are linserted between the armature 25 and the pole pieces I 2and I'Za, and the contact buttons on the front contact fingers 33 arethen adjusted to just touch the contact buttons on the iiexible Acontactiingers Si. The coils are then placed on' the cores of the relay, andthe backstrap I3 is placed on top oi the cores il and Ila. The permanentmagnet i8 is next adjusted as to strength by charging it fully and thendischarging it to a value which will give the relay the correct pick-upvalue. Finally, the release time is adjusted in a manner which I shall,describe presently, after which the relay is recalibrated, the front,back and bottom covers are assembled, and the relay is sealed.

As was pointed out hereinbefore, a relay embodying my invention isintended for use in centralized traic controlling systems for railroadswherein large numbers of quickly replaceable relays are employed, and insystems of this type when the relays are used for timing purposes it islessential that relays performing like functions should have like releasetimes to eliminate the necessity for providing excess operating margin.If the parts from which the relays are constructed are very accuratelycontrolled, both with regard to dimensions and quality of material, therelays can be made near enough alike to re- However, when relays arebuilt in large quantities on a production basis, variables are liable tocreep into both the dimensions and the quality of the material and thepresence of these variables makes it desirable to provide someconvenient means for compensating for the variations between relays.There are a variety of methods to obtain the necessary compensation, butdue to the necessary qualities the method must have, particularly whenapplied to a centralized traffic control system, for example, there arevery few methods which are entirely satisfactory. For example,temperature, vibration, humidity, time or use must not alter theadjustment once it has been made. The adjustment must not be toosensitive, so that it can be easily made. The parts must not be toocomplicated, particularly when silicon steel is used for the magneticcircuit, since silicon steel is difficult to work into shape. Above all,the adjustment must be tamper proof. That is, it must not be alteredexcept by an authorized person.

In my improved relay I prefer to accomplish the necessary adjustment byvarying the position of the backstrap I3 relative to the cores II and IIa of the electromagnet A, thereby varying the length of the air gapsbetween these members. The resulting variation in the reluctance of themagnetic circuit supplied with flux by the coils I and Ia provides ameans whereby the release time or the shunt point of the relay may bevaried minutely to accurately obtain a specic value. As shown in thedrawings, the backstrap is fastened to the upper ends of the cores IIand IIav in a preadjusted position to provide the proper release time orshunt point of the relay by means of tWo masses and d6 of a materialwhich can be applied in a liquid, molten or plastic condition and whichwill subsequently harden. A number of different materialsmay be used forthe securing means, but I prefer to use 7 per cent antimony lead becauseit pours very nicely when suiciently hot, and retains its dimensionswhile cooling. In applying this securing material, I use a mould fil orany other device capable of holding the material in place long enough topermit it to set. This mould is placed over the cores Il and Ila on topof the coils IIB and lila, and is secured in place by means of springclips 48. The backstrap I3 is placed above the cores and held theretemporarily by any suitable means such for example as a jig. lIhe relayis then checked for `release current or release time, depending uponwhich of these characteristics it is desired to accurately control. Ifthe air gaps between the backstrap I3 and the cores are not such as togive the desired characteristics, these gaps are altered to provide thedesired characteristics. There are Several ways whereby the desired airgaps may be obtained. One way to accomplish this result is to leave theends of the cores and the surfaces of the backstrap I3 opposite thecores unplated and insert non-magnetic spacers between the backstrap andthe cores. Another way to accomplish this result is to plate the coresor the backstrap or both and gradually remove a part of the plating asby a fine abrasive until the desired air gaps are obtained. A third wayof accomplishing this result is to hold the backstrap away from thecores by spring means and to gradually compress this spring means toforce the backstrap toward the cores, by means of screws provided in thejig which holds the backstrap in place, until the proper air gaps are0btained. After the desired air gaps have been obtained, the securingmeans i5 and 4% are inserted into the moulds and allowed to harden.Themould is then removed by pulling on the two clips i8 and pulling thetwo halves apart.

In case it is desired to subsequently alter the adjustment once it hasbeen made, it is only necessary to pry the backstrap oit and remove thesecuring means 45 and M from the cores and the backstrap and then repeatthe process just described.

To facilitate holding the backstrap I3 in place by means of the material45 and 45, annular grooves lil may be provided in the upper ends of thecores II and IIa and pins 50 may be inserted in the backstrap inpositions to be engaged by the fastening means.

One advantage of securing the backstrap I3 to the cores in the mannerjust described is that the necessary adjustment may be made asaccurately as measuring instruments will measure it.

Another advantage of securing the backstrap to the cores in the mannerjust described is that the adjustment is simple enough to be made byanyone capable of reading an ordinary measuring instrument.

A third advantage of securing the backstrap to the cores in the mannerjust described is that the adjustment is sensitive enough to be obtainedeasily, but is not so sensitive as to be unstable. Furthermore, afterthe adjustment has once been made, it is permanently fixed until changesin operating conditions require that the adjustment be altered when itcan readily be changed.

Afurther :advantage of, securing the backstrap to the cores in the,manner described is that this means is economicaly since the parts aresimple and the adjustment is easily made. Y

Anal. advantage ofA securingv the backstrap to the cores in the mannerdescribedris that the adjustment is fooll proof since it is necessary tohave the propery tools to remake it.

One advantage of therelay as a whole when constructed in the mannerdescribed is that since thel permanentmagnet circuit is separated fromthe electromagnet circuit, itis easy to design the magnetic circuit toproduce the desired results. Furthermore, the results obtained from therelay are the A same regardless of which direction the current flowslthrough the-operating coils l and Illa. This decreases the cost ofmanufacture as Well as ofl maintenance.

The fact that the coresY and permanent magnet pole pieces are allmoulded into the same piece as the contacts permits the elimination oftwo moulded parts and therefore greatly decreases cost. This fact alsomakes the contact frame sturdier and therefore less liable to warp orbreak. The fact that the contact frame is sturdier permits the Bakelitewalls to be much thinner, which in turn eliminates a seriousmanufacturing objection. For example, the flexible contact fingers 31are inserted into slots in the steel mould during the moulding process,the portions of the springs shown inside the Bakelite being in thecavity formed by the mould, while the portions of the springs outside ofthe Bakelite being xed by the walls of the mould. While the Bakelite issemifluid and the plunger of the mould is being closed, the plasticflows into the cavity of the mould in either direction past the Contactfingers depending on the shape of the piece and how evenly the loadingis done. This flow of semi-fluid Bakelite past a Contact finger sets upa condition on the nger similar to the conditions on a uniformly loadedbeam xed at both ends. From the theory of beams the deflection of a beamat the center, in this case the deection of the finger at the center ofthe Bakelite wall, varies directly as the fourth power of the length andinversely as the cube of the thickness. For operating reasons it is notdesirable to increase the thickness of the ngers. addition ofreinforcement is not desirable due complexity. If, however, thethickwall can be decreased from say to 1A; of an inch the deflection ofthe finger at the center is less by the ratio of 40 to 140. This factalone decreases the amount of labor necessary to assemble and adjust therelay as well as making it a more reliable instrument.

Although I have herein shown and described only one form of electricalrelay embodying my invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention. what I claim is:

1. An electrical relay comprising a plurality of flexible contact ngersrigidly supported at one end and cooperating at their free ends withfixed contact fingers, a contact operating member mounted for straightline movement between two extreme positions and provided with aplurality of projections forming slots through which the entire widthofI said flexible ngers extend intermediate their ends, the twoprojections which form each slot being disposed on opposite sides nessof the of the center line of said member and being so spaced that whenvsaidmember isin its midstroke position they will just touchV theopposite sides of the associated fingenwhereby said fingers arepositively moved between two positions in response tomovement of saidmember between its two positions but that bindingr of said fingers insaid slots is prevented, and electromagnetic means for actuatingsaid'contact operating mem.- ber between its two extreme positions.

2. An electrical relay comprising a rectangular frame of mouldedinsulating material provided in its opposite side walls adjacent. oneend thereof with slots, a plurality of flexible contactngers mouldedinto the side walls of said frame in parallel spaced relation, fixedcontact fingers moulded into` the side walls of said frame andcooperating with said flexible fingers. at their free ends, a barmounted at its ends in. said slots and providedwith a hole, a guide rodhaving one end disposed in said hole and the other end secured in a holein the opposite end wall of said frame, a contact operating memberprovided with spaced lugs provided with aligned holes which receive saidguide rod with clearance for limiting the movement of said contactoperating members to longitudinal sliding movement, means on saidcontact operating member for engaging said flexible fingers intermediatetheir ends, and electromagnetic means for moving said contact operatingmembers between two extreme positions to operate said flexible contactfingers.

3. An electrical relay comprising a rectangular frame of mouldedinsulating material provided in its opposite side walls adjacent one endthereof with slots, a plurality of flexible contact ngers moulded intothe side walls of said frame in parallel spaced relation, fixed contactngers moulded into the side walls of said frame and cooperating withsaid flexible fingers at their free ends, a bar mounted at its ends insaid slots and provided with a hole, a guide rod having one end disposedin said hole and the other end secured in a hole in the opposite endwall of said frame, a contact operating member provided with spaced lugsprovided with aligned holes which receive said guide rod with clearancefor limiting the movement of said contact operating member tolongitudinal sliding movement, means on said contact operating memberfor engaging said fingers intermediate their ends, an armature providedon said bar to prevent said contact operating member from turning, andelectromagnet means including said armature for moving said contactoperating member between two extreme positions to operate said contacts.

4. An electrical relay comprising a rectangular frame provided in itsopposite side walls adjacent one end thereof with slots and having a rstpair of cores moulded into one end wall and a second pair of coresmoulded into the other end wall, said two pairs of cores being providedat their inner ends with pole faces which lie in parallel planes,windings on one pair of cores for at times magnetizing them, a permanentmagnet engaging the other pair of cores for constantly magnetizing them,exible contact ngers moulded into the side walls of said frame inparallel spaced relation and cooperating with fixed Contact fingersmoulded into the side walls of said frame, a bar mounted at its ends insaid with a hole, a guide rod having one end disposed in said hole andthe other end secured ing member for cooperation with the pole faces ofsaid two pairs of cores respectively, said bar being provided with padswhich cooperate with the one side of one of said armatures to prevent vsaid Contact operating member from turning. Y 5. An electrical relaycomprising a rectangular frame of moulded insulating material, aplurality of flexible contact ngers moulded into the side walls of saidframe in parallel spaced relation and cooperating with fixed Contactfingers moulded into the side walls of said frame, each iixedl contactnger being moulded into the side wall opposite to that nwhch the eiiblefinger with which it cooperates is moulded, a contact operating membermounted in said frame for straight line movement between two extremepositions and provided with a plurality of projections forming slotsthrough which the entire widths of said flexible fingersextendintermediate ther'ends, alternate ones of said projections beingdisposed on opposite sides of the center line of said member and beingspaced apart such a distance that when said member is in its mid strokeposition the two projections on Opposite sides of each flexible ngerwill just touch the finger, whereby the exible fingers are positivelymoved in both directions by said member to operate the relay contactsbut that binding of the fingers within the slots formed by said projections is prevented, and electromagnetic means Vfor actuating saidcontact operating member between its two extreme positions.

CLARENCE S. SNAVELY.

